Brushes and the manufacture thereof

ABSTRACT

The invention relates to a brush provided with bristles made of an organic thermoplastic synthetic material such as nylon, particularly a tooth-brush. 
     The free ends of the bristles which are sharp and therefore able to damage soft surfaces are made round by a heat treatment. The bristle ends are preferably submitted to a laser beam treatment, the source of laser beams being preferably placed below the bristle ends. Particularly, the brush and the heat source are submitted to a relative movement and the heat treatment takes place in an atmosphere of an inert gas. 
     The invention relates also to a brush, preferably a tooth brush, having a head carrying a plurality of monofilaments made of an organic thermoplastic synthetic material. The monofilaments are tangentially welded to each other in a hole provided in said head, so that a plurality of capillary channels is obtained, said channels being open, on the one hand, on the side where the filaments protrude from the brush head and, on the other hand, on the side of the brush head opposite to the side carrying the protruding monofilaments. Impurities may thus be removed through the open-ended capillary channels, when the brush is cleaned.

FIELD OF THE INVENTION

This invention relates to improvements to brushes, particularly tobrushes having bristles made of an organic thermoplastic syntheticmaterial, such as nylon.

PRIOR ART

The known brushes comprising bristles made of an organic thermoplasticsynthetic material are provided with bristles having a free end of sucha shape that said bristles can damage and even scratch some surfaceswith which they are contacted during brushing. Thus, some brushes, suchas tooth-bruches or hair-brushes, have bristle ends which are sharp andinjure the gums and the hair skin, particularly when said brushes havebristles made of an organic synthetic material with sharp free ends. Inthe same manner, the domestic brushes provided with bristles made oforganic synthetic materials are generally useless, for example forbrushing relatively soft surfaces, such as those of waxed floors orpavements, since the ends of the bristles cause damages to saidsurfaces.

Moreover, known brushes comprise a handle connected to a head carryingbristles made of an organic thermoplastic synthetic material, such asnylon, these bristles having frequently the shape of multifilament tuftsembedded in said head.

A drawback of these known brushes, which may be tooth-brushes, is that,in spite of the cleaning treatments to which they are submitted, variousmaterials accumulate at the bottom of the bristle tufts, this being ofcourse harmful in respect of the cleanliness and in respect of thesanitary or hygienic point of view. Thus, in the case of tooth-brushes,particles resulting from the bacteria plate covering the tooth andremoved therefrom during each brushing accumulate on the face carryingthe bristles of the tooth-brush.

BRIEF DESCRIPTION OF THE INVENTION

An object of this invention is to provide a brush having bristles madeof an organic thermoplastic synthetic material, in which the free end ofthe bristles have been treated so that they are no more sharp or keen,as well as process for obtaining such a brush.

Another object of the invention is to provide a brush adapted so that noaccumulation of material of extrinsic origin, such as bacteria, occursin the bristle tufts.

This invention relates therefore to brushes with bristles made of anorganic thermoplastic synthetic material, in which the free ends of thebristles are rounded.

For obtaining the brushes with rounded bristle ends, said ends aresubmitted to a thermal treatment so as to cause a rounding of said endsby heating them at a temperature causing such a rounding, while avoidingthe bristles to stick to each other by their free ends, possibly byusing a fluid, such as water, between the bristles.

It has been found that it is possible to obtain brushes according tothis invention, i.e. brushes in which the free ends of the bristles madeof an organic thermoplastic synthetic material, such as nylon, arerounded so as to have a substantially hemispheric shape, when saidbristle ends are submitted to the action of termal beams emitted by aheat source placed under said bristle ends. In a particular embodimentof the process according to this invention, the free ends of thebristles made of an organic thermoplastic synthetic material, arrangedso as to extend downwardly, are submitted to the action of a laser beamsource placed under said free bristle ends, possibly with a relativemovement between the bristle ends and the laser beam source, so thatsaid beams sweep across the whole area provided with bristles of thebrush.

The relative movement between the laser beam source and the bristle endsand the intensity of the laser beam source are adjusted so that the freeends of the bristles are softened, so as to take substantially the shapeof a falling water drop, without causing a detaching of said roundedbristle ends, nor any sticking or adherence between the adjacent roundedbristle ends.

During the relative movement between the thermal beam source and thefree ends of the brush bristles, said source and said ends arepreferably maintained at a substantially constant distance from eachother. Thus, the source of heat beams, such as leser beams, may bedisplaced or moved in a substantially horizontal direction with respectto the downwardly directed bristles of the brush which remain in astationary position above said source of heat beams. On the contrary,the brush having its bristles extending downwardly in a verticaldirection may be displaced in a substantially horizontal direction abovethe source of heat beams, such as leser beams.

The substantially constant distance between the source of heat rays orbeams and the ends of the brush bristles may vary in accordance withvariable features, such as the nature of the bristles, the spacingbetween their free ends, the nature of the source of thermal beams, theheat intensity of the beams emitted by the source and the like.

In respect of the possible relative movement between the source of heatbeams and the bristles of the brush, the amplitude and the speed of saidmovement may also vary in accordance with various factors, such as thesurface occupied by the end of the brush bristles.

The relative movement between the source of heat beams and the brushbristles may take place in the longitudinal direction of the surfaceoccupied by the bristle ends and/or in the transverse direction of saidsurface.

The laser beam source may be used with a device for focussing the beamsor without such a device.

In order to give a regular round shape to the free bristle ends, it maybe advantageous, according to this invention, to provide in the area inwhich the bristles are located a stream of a gas, preferably an inertgas, which submits said bristles to an aspiration preferably in thedirection of the laser beams. The use of a suction stream of an inertgas, such as nitrogen, or the presence of an atmosphere of an inert gasis also advantageous since it avoids the scorching or burning of thebristles due to the heat produced by the heat source, such as the laserbeam source.

This invention also relates to a brush comprising a handle and a headcarrying bristles, in which said head carries a plurality ofmonofilaments which are substantially tangent to each other all alongtheir length, so as to form between said monofilaments a plurality ofcapillary channels which are open, on the one hand, at the free end ofthe bristles and, on the other hand, on the side of the head opposite tothe side thereof carrying protruding bristles. The monofilaments may bearranged in parallel rows the longitudinal and transverse axis of whichare perpendicular or orthogonal to each other. The monofilaments of onerow may also be staggered with respect to those of the adjacent row.

It has been found that the capillary channels formed between themonofilamentary bristles which are substantially tangent to each otherallow a removal, by capillarity, of the various materials detached fromthe brushed surface. Thus, in the case of tooth-brushes, it has beenfound that the capillary channels allow the removal of bacteriaresulting from the bacteria plate detached from the teeth during thebrushing thereof.

According to an embodiment of the invention, the bristles are formed ofa plurality of monofilaments made of an organic thermoplastic syntheticmaterial, which cross or pass through the head of the brush and aretangentially welded to each other as well as to the brush head at theirend opposite their free end, substantially in the plane of the brushhead face opposite to the face carrying the protruding bristles.

This invention relates also to a process for the manufacture of brushesof the type described in the two preceding paragraphs. According to thisprocess, a multiplicity of monofilaments made of an organicthermoplastic synthetic material, such as nylon, are engaged into anelongated hole provided in the brush head, so that the monofilaments aretangent to each other all along their length and protrude on the desireddistance with respect to one face of the head, the monofilaments aresevered or cut flush with the opposite face of the head and themonofilaments are welded to each other and to said opposite face of thehead, so that open capillary channels are formed at both ends betweenthe monofilaments.

The welding of the tangent filaments to each other and to the brush headmay be effected by heating means, for example by submitting the ends ofthe monofilaments, on the head side opposite to the side where thesemonofilaments protrude, to the action of heat beams emitted by a source,such as a laser beam source.

The welding of the monofilaments along their tangent lines and theircontact lines with the material of the head, along the edge of the holeprovided therein, is effected by arranging the source of heat beams orrays above the back face (i.e. the face opposite to the face carryingthe protruding monofilaments) of the head in front of the hole filled upwith monofilaments and by causing a relative movement between saidsource and said head, the distance between the source and the head, theintensity of the heat source and the speed of the relative movementbetween the head and the source being adjusted so as to cause saidwelding without obstructing said capillary channels, possibly due to thepresence of a fluid, such as water, in the capillary channels, duringthe welding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows schematically how the process described below has beenpractised.

FIGS. 2, 3 and 4 show a tooth brush obtained by the process according tothis invention.

DETAILED DESCRIPTION OF THE INVENTION

The following examples illustrate, in a non limitative manner, themethod for obtaining brushes having bristles to which a round shape hasbeen given.

EXAMPLES

In a first test, a tooth-brush has been used which comprised fourparallel rows of nylon bristle tufts, each tuft comprising about 30monofilaments of a diameter of about 0.2 mm, the tufts being at adistance of about 1 mm from each other at their free ends.

Said tooth-brush has been placed so that the ends of its bristle tuftsare directed downwardly at a distance of about 4 cm from a laser beamsource of the SAF type having a power of 300 watts reduced to about 20watts, arranged under the protruding ends of the bristle tufts of thetooth-brush.

The source of laser beams adjusted at a power of 20 watts has been movedat a speed of 250 cm per minute in a direction perpendicular to thebristle tufts, in such a way that the area or surface occupied by thebristle ends of the brush was completely submitted to the action of thelaser beam source.

The treated brush has been examined in a microscope and it has beenfound that ends of all the bristles had a round shape, without stickingto each other, whereas the same brush not treated in accordance withthis invention had pointed ends often provided with sharp prickles orsplinters in the vicinity of said ends.

In other tests with tooth-brushes of the above described type, thebristles of the brushes have been submitted to a small vibration during1 to 2 seconds and simultaneously to a laser beam emitter of the CO₂type of a power of 50 to 100 watts placed under the bristle end at about4 cm from the latter. In a microscope, the bristle ends of the sotreated tooth-brushes appeared perfectly round, without an noticeabledamage of the material of the bristles.

FIG. 1 of the attached drawings shows schematically how the processdescribed in the above examples has been practised.

In FIG. 1, a tooth brush 1 is maintained by any suitable means (notshown) in a horizontal position, so that the bristle tufts 2 aredirected downwardly. At a suitable distance from the ends 3 of thebristle tufts 2 a source of heat rays, such as a source of laser beams 4is placed. This laser beam source 4 can be moved along a horizontalguide shown by the line 5 in the direction of the arrows X, whereas thebrush 1 may be subjected to vibrations by means of vibrating means 18 incontact with the brush.

As pointed out above, the source of laser beams may be maintainedstationary, whereas the tooth brush in movable in a horizontaldirection.

It is also possible to move both the tooth brush and the laser beamsource simultaneously in opposite directions.

Of course, instead of possibly moving the source of laser beams, it ispossible to displace the beams themselves, for example by means of amovable mirror, the source being maintained stationary.

An atmosphere or an aspiration stream of an inert gas, such as nitrogen,argon or helium, may be provided in the area of the bristles of thebrush during the heat treatment thereof. When a stream of an inert gasis used, said stream is preferably directed in the direction of arrow Z.

Within the scope of this invention, the toothbrush may also be orientedso as to extend perpendicularly to the position shown in FIG. 1 and may,in this case, be fixed or movable perpendicularly to the arrows X infront of a heat beam source.

FIGS. 2, 3 and 4 of the attached drawings show a tooth brush obtained bythe process according to this invention, involving the formation of opencapillary channels between a multiplicity of tangent monofilaments. FIG.2 is a side view of a brush during the manufacture thereof, FIG. 3being, at a larger scale, a partial section along to the lines III--IIIof FIG. 2 and FIG. 4 being a schematic perspective view illustrating thewelding of the filaments to each other and to the head of the brush.

FIGS. 2 and 3 show a tooth-brush 1 according to this invention,comprising a handle 5 and a head 6. An elongated hole 7 is provided insaid head 5, the length and the width of said hole 7 corresponding tothe length and to the width of the bristle assembly 8. Said assembly 8comprises a multiplicity or plurality of fine monofilaments 9 made of anorganic thermoplastic synthetic material, which are parallel to eachother and form between their tangent lines 10 capillary channels 11.These channels 11 are open at the free end 12 of the filaments 9 on theside of the front face 13 of the head 6, as well as at their oppositeend 14 at the level of the back face 15 of this head. As shown by FIG.3, the filaments 9 are arranged in rows of filaments, the axis of whichare located on parallel lines both longitudinally and transversaly. Saidfilaments 9 may however be staggered. In a particular embodiment of theinvention, the tooth-brush comprises about 1250 monofilaments 9 of nylonhaving a diameter of 0.2 mm crossing completely the hole 7 having alength of 1 cm and a width of 0.5 cm. FIG. 4 shows schematically inperspective a source of laser beams 16 movable in the direction of thearrows 4 which is parallel to a brush of the type described above withreference to FIGS. 2 and 3, said source of laser beams 16 being mountedat a predetermined distance of the tooth-brush. By moving the source 16and/or the brush in the direction of the arrows Y, the laser beamsemitted by the source 16, the power of which has been adjusted to asuitable value, cause the filaments to be welded together along theirtangent lines 10 and along the lines 17 of contact (see FIG. 3) with theinner wall of the hole 7, without closing or obstructing the capillarychannels 11 at their ends 14.

The invention is of course not limited to the above described details.Although reference is essentially made in the above description totooth-brushes, this invention relates to any type of brush havingbristles made of an organic thermoplastic synthetic material.

I claim:
 1. A brush comprising a handle and a head carrying protrudingbristles made of an organic thermoplastic synthetic material, andwherein said head is provided with an aperture defined by edges, throughwhich aperture extends a first end of a plurality of monofilamentsforming said bristles, said monofilaments being substantially tangent toeach other all along their length so as to form between them a pluralityof capillary channels which are open, on the one hand, at said first endof the filaments and, on the other hand, at the free or other end of themonofilaments, the latter being welded at said first end, to each otheralong their tangent contacting lines within said aperture as well as tothe edges of said aperture, said first end of the filaments beingsubstantially flush with a side of the head opposite to the side thereoffrom which the filaments protrude.
 2. A brush according to claim 1,wherein the monofilaments are arranged in parallel rows the longitudinaland transverse axis of which are perpendicular or orthogonal to eachother.
 3. A brush according to claim 1, which is a toothbrush.